// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef MEDIA_BASE_AUDIO_BUFFER_CONVERTER_H_
#define MEDIA_BASE_AUDIO_BUFFER_CONVERTER_H_

#include <deque>
#include <memory>

#include "base/memory/ref_counted.h"
#include "base/time/time.h"
#include "media/base/audio_converter.h"
#include "media/base/audio_parameters.h"
#include "media/base/audio_timestamp_helper.h"
#include "media/base/media_export.h"

namespace media {

class AudioBuffer;
class AudioBus;

// Takes AudioBuffers in any format and uses an AudioConverter to convert them
// to a common format (usually the hardware output format).
class MEDIA_EXPORT AudioBufferConverter : public AudioConverter::InputCallback {
public:
    explicit AudioBufferConverter(const AudioParameters& output_params);
    ~AudioBufferConverter() override;

    void AddInput(const scoped_refptr<AudioBuffer>& buffer);

    // Is an output buffer available via GetNextBuffer()?
    bool HasNextBuffer();

    // This should only be called this is HasNextBuffer() returns true.
    scoped_refptr<AudioBuffer> GetNextBuffer();

    // Reset internal state.
    void Reset();

    // Reset internal timestamp state. Upon the next AddInput() call, our base
    // timestamp will be set to match the input buffer.
    void ResetTimestampState();

    int input_buffer_size_for_testing() const
    {
        return input_params_.frames_per_buffer();
    }
    int input_frames_left_for_testing() const
    {
        return input_frames_;
    }

private:
    // Callback to provide data to the AudioConverter
    double ProvideInput(AudioBus* audio_bus, uint32_t frames_delayed) override;

    // Reset the converter in response to a configuration change.
    void ResetConverter(const scoped_refptr<AudioBuffer>& input_buffer);

    // Perform conversion if we have enough data.
    void ConvertIfPossible();

    // Flush remaining output
    void Flush();

    // The output parameters.
    AudioParameters output_params_;

    // The current input parameters (we cache these to detect configuration
    // changes, so we know when to reset the AudioConverter).
    AudioParameters input_params_;

    typedef std::deque<scoped_refptr<AudioBuffer>> BufferQueue;

    // Queued up inputs (there will never be all that much data stored here, as
    // soon as there's enough here to produce an output buffer we will do so).
    BufferQueue queued_inputs_;

    // Offset into the front element of |queued_inputs_|. A ProvideInput() call
    // doesn't necessarily always consume an entire buffer.
    int last_input_buffer_offset_;

    // Buffer of output frames, to be returned by GetNextBuffer().
    BufferQueue queued_outputs_;

    // How many frames of input we have in |queued_inputs_|.
    int input_frames_;

    // Input frames in the AudioConverter's internal buffers.
    double buffered_input_frames_;

    // Ratio of sample rates, in/out.
    double io_sample_rate_ratio_;

    // Computes timestamps in terms of the output sample rate.
    AudioTimestampHelper timestamp_helper_;

    // Are we flushing everything, without regard for providing AudioConverter
    // full AudioBuses in ProvideInput()?
    bool is_flushing_;

    // The AudioConverter which does the real work here.
    std::unique_ptr<AudioConverter> audio_converter_;
};

} // namespace media

#endif // MEDIA_BASE_AUDIO_BUFFER_CONVERTER_H_
